Siloxane mitigation for laser systems

ABSTRACT

In various embodiments, the concentration and deposition of siloxane materials within components of laser systems, such as laser resonators, is reduced or minimized utilizing mitigation systems that may also supply gas having low siloxane levels into multiple different components in series or in parallel.

RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 62/915,766, filed Oct. 16, 2019, the entiredisclosure of which is hereby incorporated herein by reference.

TECHNICAL FIELD

In various embodiments, the present invention relates to laser systems,specifically apparatus and techniques for mitigating the impact ofsiloxanes in such laser systems.

BACKGROUND

High-power laser systems are utilized for a host of differentapplications, such as welding, cutting, drilling, and materialsprocessing. Such laser systems typically include a laser emitter, thelaser light from which is coupled into an optical fiber (or simply a“fiber”), and an optical system that focuses the laser light from thefiber onto the workpiece to be processed. Optical systems for lasersystems are typically engineered to produce the highest-quality laserbeam, or, equivalently, the beam with the lowest beam parameter product(BPP). The BPP is the product of the laser beam's divergence angle(half-angle) and the radius of the beam at its narrowest point (i.e.,the beam waist, the minimum spot size). That is, BPP=NA×D/2, where D isthe focusing spot (the waist) diameter and NA is the numerical aperture;thus, the BPP may be varied by varying NA and/or D. The BPP quantifiesthe quality of the laser beam and how well it can be focused to a smallspot, and is typically expressed in units of millimeter-milliradians(mm-mrad). A Gaussian beam has the lowest possible BPP, given by thewavelength of the laser light divided by pi. The ratio of the BPP of anactual beam to that of an ideal Gaussian beam at the same wavelength isdenoted M², which is a wavelength-independent measure of beam quality.

Wavelength beam combining (WBC) is a technique for scaling the outputpower and brightness from laser diodes, laser diode bars, stacks ofdiode bars, or other lasers arranged in a one- or two-dimensional array.WBC methods have been developed to combine beams along one or bothdimensions of an array of emitters. Typical WBC systems include aplurality of emitters, such as one or more diode bars, that are combinedusing a dispersive element to form a multi-wavelength beam. Each emitterin the WBC system individually resonates, and is stabilized throughwavelength-specific feedback from a common partially reflecting outputcoupler that is filtered by the dispersive element along abeam-combining dimension. Exemplary WBC systems are detailed in U.S.Pat. No. 6,192,062, filed on Feb. 4, 2000, U.S. Pat. No. 6,208,679,filed on Sep. 8, 1998, U.S. Pat. No. 8,670,180, filed on Aug. 25, 2011,and U.S. Pat. No. 8,559,107, filed on Mar. 7, 2011, the entiredisclosure of each of which is incorporated by reference herein.

Siloxanes are a class of organosilicon materials featuring thefunctional group [Si—O]_(n) and therefore possessing Si—O—Si bonds.These compounds may be linear or cyclic, and examples of siloxanesinclude hexamethyldisiloxane, octamethyltrisiloxane,hexamethylcyclotrisiloxane, and octamethylcyclotetrasiloxane. Siloxaneshave many commercial and industrial applications, including lasersystems, because of their hydrophobicity, low thermal conductivity, andhigh flexibility. Unfortunately, the power degradation of many laseremitters, for example GaN- and InGaN-based diode lasers emitting beamsat visible (or shorter) wavelengths, can accelerate due to exposure tosiloxanes, which may enter laser systems from the ambient atmosphere(from, e.g., outgassing from materials containing silicones, which arecommon in cosmetics, cleaning products, and pharmaceutical products) orevolve within laser systems due to outgassing of components therewithin(e.g., components including, consisting essentially of, or consisting ofone or more silicones, e.g., gaskets, seals, epoxies, adhesives, etc.).Siloxanes within the laser system may be “captured” by the nitride-basedlaser emitter and attach to the laser emitter facet, resulting in powerdegradation. Such degradation may even be accelerated as the power andemitted light intensity of the laser emitter increases, as desired forpresent and future laser systems.

One technique to at least partially address this issue is thefabrication and installation of laser devices within a low-siloxaneenvironment; however, the systems must then be hermetically sealed toprevent entry of siloxanes from the outside environment duringoperation, which can be challenging. In addition, such solutions do notadequately address siloxanes produced by outgassing. Thus, there is aneed for systems and techniques for reducing or minimizing the exposureof laser-system components to siloxanes, thereby mitigating theirdeleterious effects.

SUMMARY

In accordance with embodiments of the present invention,siloxane-mitigation systems and techniques are utilized to reduce orminimize the exposure of the components internal to laser devices,including beam emitters, to siloxanes, and thereby reduce or minimizesiloxane-induced degradation of performance and reliability. In variousembodiments, one or more beam emitters are disposed within a “lasercavity” of a partially or fully sealed environment, also referred toherein as an “emitter module,” a “resonator module,” or a “resonator.”The “laser cavity” refers to the portion of the resonator in which thebeam emitters are disposed, and the laser cavity may be sealed from oropen to one or more additional internal portions of the resonator, whichtypically contains other components such as optical elements, electricalconnections, cooling systems and/or reservoirs, etc. In variousembodiments, the laser cavity is connected to a closed-loop or open-loopcirculation system that replaces and/or recirculates the gas internal tothe laser cavity in order to remove siloxanes from the laser-cavityinternal environment. In some embodiments, the circulation system formsa closed loop, in which the gas is pumped from the laser cavity to asiloxane-mitigation system, from which it is pumped back into the lasercavity. In other environments, the circulation system forms an openloop, in which gas (e.g., air) is pumped into the siloxane-mitigationsystem and thence to the laser cavity, where it is allowed to escape tothe surrounding ambient (i.e., without being pumped back to thesiloxane-mitigation system). The positive pressure created in sucharrangements helps to prevent ingress of siloxanes into the lasercavity.

In various embodiments, the circulation system is operated continuously,thereby continuously exchanging the gas within the laser cavity with gashaving a lower concentration of (or even being substantially free of)siloxanes therewithin. In other embodiments, the circulation system isoperated at intervals, which may be irregularly or regularly scheduled,or the circulation system is operated on demand (e.g., when initiated bya human operator). For example, the laser cavity may include one or moremonitors or sensors for sensing siloxane concentration, and thecirculation system may operate to pump new gas into the laser cavitywhen the siloxane concentration reaches a threshold level.

In other embodiments, the circulation system may be operated duringlaser emission, in order to suppress generation and deposition ofactivated, higher-energy siloxane species. Particularly in laser systemsincorporating laser emitters emitting at short wavelengths (e.g.,visible light such as blue light, or even ultraviolet light), thehigh-energy laser light may activate siloxane molecules in the lasersystem illuminated by the light; that is, illumination by the light mayradicalize or break the molecular structure of the siloxane species,rendering it more reactive (i.e., at a higher-energy state). Suchactivated species may react with other siloxane species in the lasersystem and be deposited at the laser emitter (e.g., at the emissionfacet). If the laser emitter has an oxide coating (e.g., a protectiveand/or anti-reflective overlayer), such deleterious deposition may beaccelerated, given the large binding energy between silicon and oxygen.Thus, in various embodiments, the circulation system may be initiatedprior to operation (i.e., laser emission) and turned off after laseremission and/or during periods during which laser energy is not beingactively emitted by the system. In various embodiments, the circulationsystem may be initiated a short time (e.g., up to 1 minute, up to 2minutes, up to 5 minutes, or up to 10 minutes) before operation, toreduce or minimize siloxane concentration within the system prior tooperation. Similarly, the circulation system may continue to operate fora short time (e.g., up to 1 minute, up to 2 minutes, up to 5 minutes, orup to 10 minutes) after operation, in order to reduce or minimize thepresence of siloxanes produced during operation.

In various embodiments, the circulation system operates on multipledifferent laser cavities or resonators in series or in parallel.Similarly, in various embodiments the circulation system may operate notonly on laser cavities housing beam emitters, but also other portions orcomponents (which may also be sealed) of the laser system, such as fiberoptic modules. Therefore, descriptions herein involving “laser cavities”may be understood to equally apply to other components, systems, orsub-systems of a laser device or apparatus. In various embodiments, thecirculation/siloxane-mitigation system may be utilized with one or moreenclosed components such as laser resonators. As used herein, and“enclosed” component has one or more sealed areas, e.g., a laser cavitycontaining one or more beam emitters therewithin; that is, an enclosedcomponent need not be, but may be, sealed in its entirety.

In various embodiments, the siloxane-mitigation system may include,consist essentially of, or consist of a material for adsorption of thesiloxane from the gas stream, such as activated carbon, silica gel,polymer beads, or one or more molecular sieves. In various embodiments,the siloxane-mitigation system may include, consist essentially of, orconsist of a material for absorption of the siloxane from the gasstream, such as organic solvents, mineral oil, or even water. In thesiloxane-mitigation system, the gas to be pumped into the laser cavitymay flow over and/or through (e.g., bubbled through) one or more suchmaterials for adsorption and/or absorption of siloxanes from the gas.Thus, in various embodiments, removing siloxanes from the gas mayintroduce moisture (e.g., a quantity of one or more liquids) into thegas. In some embodiments, the siloxane-mitigation system mayalternatively, or in addition, include, consist essentially of, orconsist of a remediation system that removes siloxane from the gasstream via condensation (e.g., one or more cooling systems) and/orreaction (such as catalysis). In various embodiments, thesiloxane-mitigation system may also include a drying system (e.g., acontainer having therewithin one or more desiccants) to remove moisturefrom the gas prior to introduction of the gas into the laser cavity.

In accordance with embodiments of the invention, laser resonatorsinterfacing with a siloxane-mitigation system may include one or morelaser emitters emitting light in the visible-wavelength regime (orshorter wavelengths such as ultraviolet wavelengths), and/or may becomposed, at least in part, by nitride-based semiconductor materialssuch as GaN and InGaN. While systems utilizing longer-wavelengthemitters may not exhibit power degradation due to siloxane exposure tothe same extent, embodiments of the invention may also be utilized withsuch emitters for long-term stability and reliability.

Resonators in accordance with embodiments of the invention may includeone or more components, interfaces, and/or control systems detailed inU.S. patent application Ser. No. 15/660,134, filed on Jul. 26, 2017 (the'134 application), and/or U.S. patent application Ser. No. 16/421,728,filed on May 24, 2019, the entire disclosure of each of which isincorporated by reference herein. For example, resonator modules inaccordance with embodiments of the invention may include electrical andoptical interfaces that interface with complementary features on abeam-combining enclosure in which the individual beams from the modulesare combined into a single output beam (and, in some embodiments,coupled into an optical fiber). The optical and electrical interfacesfacilitate the easy replacement of input laser sources with a minimalamount, if any, of source alignment. The emitter modules may beinsertable into and mate with input receptacles disposed in or on theenclosure in which the input beams are combined to form the output beam.Resonator modules may connect mechanically, electrically, and/oroptically with one of multiple input receptacles disposed in or on (orforming portions of) the enclosure for the beam-combining optics.

As known to those of skill in the art, lasers are generally defined asdevices that generate visible or invisible light through stimulatedemission of light. Lasers generally have properties that make themuseful in a variety of applications, as mentioned above. Common lasertypes include semiconductor lasers (e.g., laser diodes and diode bars),solid-state lasers, fiber lasers, and gas lasers. A laser diode isgenerally based on a simple diode structure that supports the emissionof photons (light). However, to improve efficiency, power, beam quality,brightness, tunability, and the like, this simple structure is generallymodified to provide a variety of many practical types of laser diodes.Laser diode types include small edge-emitting varieties that generatefrom a few milliwatts up to roughly half a watt of output power in abeam with high beam quality. Structural types of diode lasers includedouble hetero-structure lasers that feature a layer of low bandgapmaterial sandwiched between two high bandgap layers; quantum well lasersthat include a very thin middle (quantum well) layer resulting in highefficiency and quantization of the laser's energy; multiple quantum welllasers that include more than one quantum well layer to improve gaincharacteristics; quantum wire or quantum sea (dots) lasers that replacethe middle layer with a wire or dots to produce higher-efficiencyquantum well lasers; quantum cascade lasers that enable laser action atrelatively long wavelengths that may be tuned by altering the thicknessof the quantum layer; separate confinement heterostructure lasers, whichare the most common commercial laser diode and include another twolayers above and below the quantum well layer to efficiently confine thelight produced; distributed feedback lasers, which are commonly used indemanding optical communication applications and include an integrateddiffraction grating that facilitates generating a stable wavelength setduring manufacturing by reflecting a single wavelength back to the gainregion; vertical-cavity surface-emitting lasers (VCSELs), which have adifferent structure that other laser diodes in that light is emittedfrom its surface rather than from its edge; and vertical-external-cavitysurface-emitting lasers (VECSELs) and external-cavity diode lasers,which are tunable lasers that use mainly double heterostructure diodesand include gratings or multiple-prism grating configurations.External-cavity diode lasers are often wavelength-tunable and exhibit asmall emission line width. Laser diode types also include a variety ofhigh power diode-based lasers including: broad area lasers that arecharacterized by multi-mode diodes with oblong output facets andgenerally have poor beam quality but generate a few watts of power;tapered lasers that are characterized by astigmatic mode diodes withtapered output facets that exhibit improved beam quality and brightnesswhen compared to broad area lasers; ridge waveguide lasers that arecharacterized by elliptical mode diodes with oval output facets; andslab-coupled optical waveguide lasers (SCOWL) that are characterized bycircular mode diodes with output facets and may generate watt-leveloutput in a diffraction-limited beam with nearly a circular profile.

A diode-laser bar is a type of semiconductor laser containing aone-dimensional array of broad-area emitters or alternatively containingsub arrays containing, e.g., 10-20 narrow stripe emitters. A broad-areadiode bar typically contains, for example, 19-49 emitters, each havingdimensions on the order of, e.g., 1 μm×100 μm. The beam quality alongthe 1 μm dimension or fast-axis is typically diffraction-limited. Thebeam quality along the 100 μm dimension or slow-axis or array dimensionis typically many times diffraction-limited. Typically, a diode bar forcommercial applications has a laser resonator length of the order of 1to 4 mm, is about 10 mm wide and generates tens of watts of outputpower. Most diode bars operate in the wavelength region from 780 to 1070nm, with the wavelengths of 808 nm (for pumping neodymium lasers) and940 nm (for pumping Yb:YAG) being most prominent. The wavelength rangeof 915-976 nm is used for pumping erbium-doped or ytterbium-dopedhigh-power fiber lasers and amplifiers.

Embodiments of the present invention may couple one or more laser beamsinto an optical fiber. In various embodiments, the optical fiber hasmultiple cladding layers surrounding a single core, multiple discretecore regions (or “cores”) within a single cladding layer, or multiplecores surrounded by multiple cladding layers.

Herein, “optical elements” may refer to any of lenses, mirrors, prisms,gratings, and the like, which redirect, reflect, bend, or in any othermanner optically manipulate electromagnetic radiation, unless otherwiseindicated. Herein, beam emitters, emitters, or laser emitters, or lasersinclude any electromagnetic beam-generating device such as semiconductorelements, which generate an electromagnetic beam, but may or may not beself-resonating. These also include fiber lasers, disk lasers, non-solidstate lasers, etc. Generally, each emitter includes a back reflectivesurface, at least one optical gain medium, and a front reflectivesurface. The optical gain medium increases the gain of electromagneticradiation that is not limited to any particular portion of theelectromagnetic spectrum, but that may be visible, infrared, and/orultraviolet light. An emitter may include or consist essentially ofmultiple beam emitters such as a diode bar configured to emit multiplebeams. The input beams received in the embodiments herein may besingle-wavelength or multi-wavelength beams combined using varioustechniques known in the art. In addition, references to “lasers,” “laseremitters,” or “beam emitters” herein include not only single-diodelasers, but also diode bars, laser arrays, diode bar arrays, and singleor arrays of vertical cavity surface-emitting lasers (VCSELs). Herein,it is understood that references to different “wavelengths” encompassdifferent “ranges of wavelengths,” and the wavelength (or color) of alaser corresponds to the primary wavelength thereof; that is, emittersmay emit light having a finite band of wavelengths that includes (andmay be centered on) the primary wavelength.

Laser systems having siloxane-mitigation systems and utilizingsiloxane-mitigation techniques in accordance with embodiments of thepresent invention may be utilized to process a workpiece such that thesurface of the workpiece is physically altered and/or such that afeature is formed on or within the surface, in contrast with opticaltechniques that merely probe a surface with light (e.g., reflectivitymeasurements). Exemplary processes in accordance with embodiments of theinvention include cutting, welding, drilling, and soldering. Variousembodiments of the invention also process workpieces at one or morespots or along a one-dimensional processing path, rather thansimultaneously flooding all or substantially all of the workpiecesurface with radiation from the laser beam. In general, processing pathsmay be curvilinear or linear, and “linear” processing paths may featureone or more directional changes, i.e., linear processing paths may becomposed of two or more substantially straight segments that are notnecessarily parallel to each other.

Various embodiments of the invention may be utilized with laser systemsfeaturing techniques for varying BPP of their output laser beams, suchas those described in U.S. patent application Ser. No. 14/632,283, filedon Feb. 26, 2015, and U.S. patent application Ser. No. 15/188,076, filedon Jun. 21, 2016, the entire disclosure of each of which is incorporatedherein by reference.

Laser systems in accordance with various embodiments of the presentinvention may also include a delivery mechanism that directs the laseroutput onto the workpiece while causing relative movement between theoutput and the workpiece. For example, the delivery mechanism mayinclude, consist essentially of, or consist of a laser head fordirecting and/or focusing the output toward the workpiece. The laserhead may itself be movable and/or rotatable relative to the workpiece,and/or the delivery mechanism may include a movable gantry or otherplatform for the workpiece to enable movement of the workpiece relativeto the output, which may be fixed in place.

In various embodiments of the present invention, the laser beamsutilized for processing of various workpieces may be delivered to theworkpiece via one or more optical fibers (or “delivery fibers”).Embodiments of the invention may incorporate optical fibers having manydifferent internal configurations and geometries. Such optical fibersmay have one or more core regions and one or more cladding regions. Forexample, the optical fiber may include, consist essentially of, orconsist of a central core region and an annular core region separated byan inner cladding layer. One or more outer cladding layers may bedisposed around the annular core region. Embodiments of the inventionmay be utilized with and/or incorporate optical fibers havingconfigurations described in U.S. patent application Ser. No. 15/479,745,filed on Apr. 5, 2017, and U.S. patent application Ser. No. 16/675,655,filed on Nov. 6, 2019, the entire disclosure of each of which isincorporated by reference herein.

Structurally, optical fibers in accordance with embodiments of theinvention may include one or more layers of high and/or low refractiveindex beyond (i.e., outside of) an exterior cladding without alteringthe principles of the present invention. Various ones of theseadditional layers may also be termed claddings or coatings, and may notguide light. Optical fibers may also include one or more cores inaddition to those specifically mentioned. Such variants are within thescope of the present invention. Various embodiments of the invention donot incorporate mode strippers in or on the optical fiber structure.Similarly, the various layers of optical fibers in accordance withembodiments of the invention are continuous along the entire length ofthe fiber and do not contain holes, photonic-crystal structures, breaks,gaps, or other discontinuities therein.

Optical fibers in accordance with the invention may be multi-mode fibersand therefore support multiple modes therein (e.g., more than three,more than ten, more than 20, more than 50, or more than 100 modes). Inaddition, optical fibers in accordance with the invention are generallypassive fibers, i.e., are not doped with active dopants (e.g., erbium,ytterbium, thulium, neodymium, dysprosium, praseodymium, holmium, orother rare-earth metals) as are typically utilized for pumped fiberlasers and amplifiers. Rather, dopants utilized to select desiredrefractive indices in various layers of fibers in accordance with thepresent invention are generally passive dopants that are not excited bylaser light, e.g., fluorine, titanium, germanium, and/or boron. Thus,optical fibers, and the various core and cladding layers thereof inaccordance with various embodiments of the invention may include,consist essentially of, or consist of glass, such as substantially purefused silica and/or fused silica, and may be doped with fluorine,titanium, germanium, and/or boron. Obtaining a desired refractive indexfor a particular layer or region of an optical fiber in accordance withembodiments of the invention may be accomplished (by techniques such asdoping) by one of skill in the art without undue experimentation.Relatedly, optical fibers in accordance with embodiments of theinvention may not incorporate reflectors or partial reflectors (e.g.,grating such as Bragg gratings) therein or thereon. Fibers in accordancewith embodiments of the invention are typically not pumped with pumplight configured to generate laser light of a different wavelength.Rather, fibers in accordance with embodiments of the invention merelypropagate light along their lengths without changing its wavelength.Optical fibers utilized in various embodiments of the invention mayfeature an optional external polymeric protective coating or sheathdisposed around the more fragile glass or fused silica fiber itself.

In addition, systems and techniques in accordance with embodiments ofthe present invention are typically utilized for materials processing(e.g., cutting, drilling, etc.), rather than for applications such asoptical communication or optical data transmission. Thus, laser beams,which may be coupled into fibers in accordance with embodiments of theinvention, may have wavelengths different from the 1.3 μm or 1.5 μmutilized for optical communication. In fact, fibers utilized inaccordance with embodiments of the present invention may exhibitdispersion at one or more (or even all) wavelengths in the range ofapproximately 1260 nm to approximately 1675 nm utilized for opticalcommunication.

In an aspect, embodiments of the invention feature a laser apparatusincluding, consisting essentially of, or consisting of an enclosed lasercavity comprising one or more beam emitters therewithin, a gas inlet forpermitting ingress of gas into the laser cavity, a pump for supplyinggas to the gas inlet, and a siloxane-mitigation system configured toremove siloxanes from gas supplied to the gas inlet by the pump.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. At least one beam emitter may include,consist essentially of, or consist of one or more nitride semiconductormaterials. At least one beam emitter may include, consist essentiallyof, or consist of GaN, AlGaN, InGaN, AlN, InN, and/or an alloy ormixture thereof. The laser cavity may be configured to allow leakage ofthe supplied gas therefrom i.e., may not have a single dedicated gasoutlet). The apparatus may include a gas outlet for permitting orconfigured to permit egress of gas from the laser cavity. The pump maybe fluidly connected to the gas outlet. The gas outlet may be configuredto release gas into a surrounding ambient and/or into an exhaust system.The apparatus may include a desiccant positioned to remove moisture fromgas supplied to the gas inlet by the pump. The desiccant may bedifferent from, and/or positioned outside of, the siloxane-mitigationsystem. The siloxane-mitigation system may include, consist essentiallyof, or consist of a siloxane-adsorbing material and/or asiloxane-absorbing material. The siloxane-mitigation system may include,consist essentially of, or consist of activated carbon, silica gel,polymer beads, and/or one or more molecular sieves. Thesiloxane-mitigation system may include, consist essentially of, orconsist of an organic solvent, mineral oil, or water. Thesiloxane-mitigation system may include, consist essentially of, orconsist of a remediation system configured to remove siloxanes from thegas via condensation and/or reaction. The siloxane-mitigation system mayinclude, consist essentially of, or consist of a liquid over and/orthrough which gas supplied to the gas inlet is flowed.

The apparatus may include one or more sensors configured to detectsiloxanes within the laser cavity and/or within one or more conduitsfluidly connected to the gas inlet, the pump, and/or thesiloxane-mitigation system. The apparatus may include a computer-basedcontroller configured to introduce gas into the gas inlet via operationof the pump and/or to control the siloxane-mitigation system. Theapparatus may include one or more sensors configured to detect siloxaneswithin the laser cavity and/or within one or more conduits fluidlyconnected to the gas inlet, the pump, and/or the siloxane-mitigationsystem, and the controller may be responsive to signals received fromthe one or more sensors. The controller may be configured to introducegas into the gas inlet only when a siloxane concentration detected by atleast one of the sensors exceeds a threshold. The controller may beconfigured to introduce gas into the gas inlet continuously, at leastduring operation of the one or more beam emitters. The controller may beconfigured to introduce gas into the gas inlet at regular intervals,e.g., whether or more the one or more beam emitters are operating toemit beams. The controller may be configured to introduce gas into thegas inlet upon receipt of a command from an operator. The laser cavitymay be hermetically sealed. The laser cavity may include therewithin oneor more materials that produce siloxanes via outgassing.

The one or more beam emitters may include, consist essentially of, orconsist of a plurality of beam emitters. The laser cavity may includetherewithin (A) a dispersive element configured to receive beams emittedby the plurality of emitters and combine the beams into amulti-wavelength beam, and disposed optically downstream of thedispersive element, a partially reflective output coupler configured to(i) receive the multi-wavelength beam, (ii) transmit a first portion ofthe multi-wavelength beam as an output beam, and (iii) reflect a secondportion of the multi-wavelength beam back toward the dispersive element.The laser cavity may include therewithin (A) a plurality of slow-axiscollimation lenses disposed optically downstream of the plurality ofbeam emitters, each slow-axis collimation lens configured to receive oneor more beams from one of the beam emitters, and (B) a plurality offolding mirrors disposed optically downstream of the slow-axiscollimation lenses and optically upstream of the dispersive element. Theapparatus may include a fluid coolant cavity disposed beneath theplurality of beam emitters, a fluid inlet configured to supply fluidcoolant to the fluid coolant cavity, and a fluid outlet configured toexhaust fluid coolant from the fluid coolant cavity.

In another aspect, embodiments of the invention include a laserapparatus including, consisting essentially of, or consisting of a lasersystem including, consisting essentially of, or consisting of aplurality of enclosed components, a plurality of gas inlets, a pluralityof gas outlets, an inlet manifold fluidly coupled to the plurality ofgas inlets, a pump for supplying gas to the inlet manifold, and asiloxane-mitigation system configured to remove siloxanes from gassupplied to the inlet manifold by the pump. At least one of thecomponents includes one or more beam emitters therewithin. Each gasinlet is configured to permit ingress of gas into a different component.Each gas outlet is configured to permit egress of gas from a differentcomponent.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. One or more of the components may notinclude a beam emitter therewithin. At least one beam emitter mayinclude, consist essentially of, or consist of one or more nitridesemiconductor materials. At least one beam emitter may include, consistessentially of, or consist of GaN, AlGaN, InGaN, AlN, InN, and/or analloy or mixture thereof. The apparatus may include an outlet manifoldfluidly coupled to the plurality of gas outlets. The pump may be fluidlyconnected to the outlet manifold. The outlet manifold may be configuredto release gas into a surrounding ambient and/or into an exhaust system.The plurality of gas outlets may be configured to release gas into asurrounding ambient and/or into an exhaust system. The apparatus mayinclude a desiccant positioned to remove moisture from gas supplied tothe inlet manifold by the pump. The desiccant may be different from,and/or positioned outside of, the siloxane-mitigation system. Thesiloxane-mitigation system may include, consist essentially of, orconsist of a siloxane-adsorbing material and/or a siloxane-absorbingmaterial. The siloxane-mitigation system may include, consistessentially of, or consist of activated carbon, silica gel, polymerbeads, and/or one or more molecular sieves. The siloxane-mitigationsystem may include, consist essentially of, or consist of an organicsolvent, mineral oil, or water. The siloxane-mitigation system mayinclude, consist essentially of, or consist of a remediation systemconfigured to remove siloxanes from the gas via condensation and/orreaction. The siloxane-mitigation system may include, consistessentially of, or consist of a liquid over and/or through which gassupplied to the inlet manifold is flowed.

The apparatus may include one or more sensors configured to detectsiloxanes within at least one component and/or within one or moreconduits fluidly connected to the pump, at least one component, theinlet manifold, and/or the siloxane-mitigation system. The apparatus mayinclude a computer-based controller configured to introduce gas into theinlet manifold via operation of the pump and/or to control thesiloxane-mitigation system. The apparatus may include one or moresensors configured to detect siloxanes within at least one componentand/or within one or more conduits fluidly connected to the pump, atleast one component, the inlet manifold, and/or the siloxane-mitigationsystem, and the controller may be responsive to signals received fromthe one or more sensors. The controller may be configured to introducegas into the inlet manifold only when a siloxane concentration detectedby at least one of the sensors exceeds a threshold. The controller maybe configured to introduce gas into the inlet manifold continuously, atleast during operation of the one or more beam emitters. The controllermay be configured to introduce gas into the inlet manifold at regularintervals, e.g., whether or more the one or more beam emitters areoperating to emit beams. The controller may be configured to introducegas into the inlet manifold upon receipt of a command from an operator.At least one component may be hermetically sealed. At least onecomponent may include therewithin one or more materials that producesiloxanes via outgassing.

At least one of the components may be, include, consist essentially of,or consist of a laser resonator having an enclosed laser cavity. Thelaser cavity may include therewithin (A) a plurality of beam emitters,(B) a dispersive element configured to receive beams emitted by theplurality of emitters and combine the beams into a multi-wavelengthbeam, and (C) disposed optically downstream of the dispersive element, apartially reflective output coupler configured to (i) receive themulti-wavelength beam, (ii) transmit a first portion of themulti-wavelength beam as an output beam, and (iii) reflect a secondportion of the multi-wavelength beam back toward the dispersive element.The laser cavity may include therewithin (A) a plurality of slow-axiscollimation lenses disposed optically downstream of the plurality ofbeam emitters, each slow-axis collimation lens configured to receive oneor more beams from one of the beam emitters, and (B) a plurality offolding mirrors disposed optically downstream of the slow-axiscollimation lenses and optically upstream of the dispersive element. Thelaser resonator may include a fluid coolant cavity disposed beneath theplurality of beam emitters, a fluid inlet configured to supply fluidcoolant to the fluid coolant cavity, and a fluid outlet configured toexhaust fluid coolant from the fluid coolant cavity.

The plurality of components may include, consist essentially of, orconsist of a plurality of laser resonators. Each laser resonator mayinclude a plurality of beam emitters therewithin and be configured tocombine beams emitted by the beam emitters into a combined beam. Theplurality of components may include (A) a beam-combining moduleconfigured to receive the combined beams from the laser resonators andcombine the combined beams into an output beam, and (B) a fiber opticmodule configured to receive the output beam from the beam-combiningmodule and supply the output beam to an optical fiber.

In yet another aspect, embodiments of the invention feature a laserapparatus including, consisting essentially of, or consisting of a lasersystem including, consisting essentially of, or consisting of aplurality of enclosed components, a pump for supplying gas to the gasinlet of a first one of the components, and a siloxane-mitigation systemconfigured to remove siloxanes from gas supplied by the pump. At leastone of the components includes one or more beam emitters therewithin.Each component includes a gas inlet configured to permit ingress of gasinto the component and a gas outlet configured to permit egress of gasout of the component. The components are fluidly connected to each otherin series (e.g., via their gas inlets and gas outlets and conduitsconnecting them). The gas supplied by the pump supplied flowssequentially into and out of each of the series-connected components.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The apparatus may include an inletmanifold fluidly coupled to the gas inlet of the first one of thecomponents. The pump may supply gas to the inlet manifold for supply tothe gas inlet of the first one of the components. One or more of thecomponents may not include a beam emitter therewithin. At least one beamemitter may include, consist essentially of, or consist of one or morenitride semiconductor materials. At least one beam emitter may include,consist essentially of, or consist of GaN, AlGaN, InGaN, AlN, InN,and/or an alloy or mixture thereof. The apparatus may include an outletmanifold fluidly coupled to a gas outlet of a last one of the components(e.g., the last one in the series connection of the components). Thepump may be fluidly connected to the outlet manifold. The outletmanifold may be configured to release gas into a surrounding ambientand/or into an exhaust system. The gas outlet of a last one of thecomponents may be fluidly connected to the pump. The gas outlet of alast one of the components may be configured to release gas into asurrounding ambient and/or into an exhaust system. The apparatus mayinclude a desiccant positioned to remove moisture from gas supplied bythe pump. The desiccant may be different from, and/or positioned outsideof, the siloxane-mitigation system. The siloxane-mitigation system mayinclude, consist essentially of, or consist of a siloxane-adsorbingmaterial and/or a siloxane-absorbing material. The siloxane-mitigationsystem may include, consist essentially of, or consist of activatedcarbon, silica gel, polymer beads, and/or one or more molecular sieves.The siloxane-mitigation system may include, consist essentially of, orconsist of an organic solvent, mineral oil, or water. Thesiloxane-mitigation system may include, consist essentially of, orconsist of a remediation system configured to remove siloxanes from thegas via condensation and/or reaction. The siloxane-mitigation system mayinclude, consist essentially of, or consist of a liquid over and/orthrough which gas supplied by the pump is flowed.

The apparatus may include one or more sensors configured to detectsiloxanes within at least one component and/or within one or moreconduits fluidly connected to the pump, at least one component, and/orthe siloxane-mitigation system. The apparatus may include acomputer-based controller configured to operate the pump and/or tocontrol the siloxane-mitigation system. The apparatus may include one ormore sensors configured to detect siloxanes within at least onecomponent and/or within one or more conduits fluidly connected to thepump, at least one component, and/or the siloxane-mitigation system, andthe controller may be responsive to signals received from the one ormore sensors. The controller may be configured to operate the pump onlywhen a siloxane concentration detected by at least one of the sensorsexceeds a threshold. The controller may be configured to operate thepump continuously, at least during operation of the one or more beamemitters. The controller may be configured to operate the pump atregular intervals, e.g., whether or more the one or more beam emittersare operating to emit beams. The controller may be configured to operatethe pump upon receipt of a command from an operator. At least onecomponent may be hermetically sealed. At least one component may includetherewithin one or more materials that produce siloxanes via outgassing.

At least one of the components may be, include, consist essentially of,or consist of a laser resonator having an enclosed laser cavity. Thelaser cavity may include therewithin (A) a plurality of beam emitters,(B) a dispersive element configured to receive beams emitted by theplurality of emitters and combine the beams into a multi-wavelengthbeam, and (C) disposed optically downstream of the dispersive element, apartially reflective output coupler configured to (i) receive themulti-wavelength beam, (ii) transmit a first portion of themulti-wavelength beam as an output beam, and (iii) reflect a secondportion of the multi-wavelength beam back toward the dispersive element.The laser cavity may include therewithin (A) a plurality of slow-axiscollimation lenses disposed optically downstream of the plurality ofbeam emitters, each slow-axis collimation lens configured to receive oneor more beams from one of the beam emitters, and (B) a plurality offolding mirrors disposed optically downstream of the slow-axiscollimation lenses and optically upstream of the dispersive element. Thelaser resonator may include a fluid coolant cavity disposed beneath theplurality of beam emitters, a fluid inlet configured to supply fluidcoolant to the fluid coolant cavity, and a fluid outlet configured toexhaust fluid coolant from the fluid coolant cavity.

The plurality of components may include, consist essentially of, orconsist of a plurality of laser resonators. Each laser resonator mayinclude a plurality of beam emitters therewithin and be configured tocombine beams emitted by the beam emitters into a combined beam. Theplurality of components may include (A) a beam-combining moduleconfigured to receive the combined beams from the laser resonators andcombine the combined beams into an output beam, and (B) a fiber opticmodule configured to receive the output beam from the beam-combiningmodule and supply the output beam to an optical fiber.

In another aspect, embodiments of the invention feature a method ofemission (e.g., reliable emission) of one or more beams by a laserapparatus. One or more beam emitters disposed within an enclosed lasercavity are operated to form one or more beams. Thereduring, gas withinthe laser cavity is exchanged with new gas having a lower concentrationof siloxanes therewithin.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. Exchanging gas within the laser cavitymay include, consist essentially of, or consist of removing siloxanesfrom the new gas and thereafter supplying the new gas to the lasercavity. Siloxanes may be removed from the new gas via adsorption and/orabsorption. Siloxanes may be adsorbed by activated carbon, silica gel,polymer beads, and/or one or more molecular sieves. Siloxanes may beabsorbed by an organic solvent, mineral oil, and/or water. Siloxanes maybe removed from the new gas via condensation and/or reaction. Siloxanesmay be removed from the new gas by flowing the new gas over and/orthrough a liquid. The laser cavity may be configured to allow leakage ofgas therefrom. Exchanging gas within the laser cavity may include,consist essentially of, or consist of supplying new gas to a gas inletfluidly coupled to the laser cavity and exhausting gas via a gas outletfluidly coupled to the laser cavity. The gas outlet may be configured torelease gas into a surrounding ambient and/or into an exhaust system.Moisture may be removed from the new gas prior to introduction thereofinto the laser cavity. Moisture may be removed from the new gas after,and/or separately, from siloxane removal from the new gas.

A concentration of siloxanes within the laser cavity, within new gassupplied to the laser cavity, and/or gas exhausted from the laser cavitymay be detected. Gas may be exchanged within the laser cavity only whena detected siloxane concentration exceeds a threshold. Gas may beexchanged within the laser cavity continuously during operation of theone or more beam emitters. Gas may be exchanged within the laser cavityat regular intervals, e.g., only when the beam emitters are operating orwhether or not the beam emitters are operating. Gas may be exchangedwithin the laser cavity upon receipt of a command from an operator(e.g., a human operator). The laser cavity may be hermetically sealed.The laser cavity may include therewithin one or more materials thatproduce siloxanes via outgassing. At least one beam emitter may include,consist essentially of, or consist of one or more nitride semiconductormaterials. At least one beam emitter may include, consist essentiallyof, or consist of GaN, AlGaN, InGaN, AlN, InN, and/or an alloy ormixture thereof.

The one or more beam emitters may include, consist essentially of, orconsist of a plurality of beam emitters. Beams emitted by the beamemitters may each have a different wavelength. Beams emitted by theplurality of beam emitters may be combined into a combined and/ormulti-wavelength beam. A first portion of the combined and/ormulti-wavelength beam may be transmitted out of the laser cavity as anoutput beam. A second portion of the combined and/or multi-wavelengthbeam may be directed back to the plurality of beam emitters to stabilizeemission thereof (e.g., to form external lasing cavities). The pluralityof beam emitters may be cooled, e.g., via flow of a fluid coolant. Aworkpiece may be processed with the output beam. Processing theworkpiece may include, consist essentially of, or consist of cutting,welding, etching, annealing, drilling, soldering, and/or brazing.Processing the workpiece may include, consist essentially of, or consistof physically altering at least a portion of a surface of the workpiece.

In yet another aspect, embodiments of the invention feature a method ofemission (e.g., reliable emission) of one or more beams by a laserapparatus. The laser apparatus includes, consists essentially of, orconsists of a plurality of enclosed components. At least one of thecomponents includes one or more beam emitters therewithin. Each of thecomponents includes gas therewithin. One or more of the components maybe sealed or enclosed. The one or more beam emitters are operated toform one or more beams. Thereduring, new gas is supplied to each of thecomponents in parallel. The new gas has a lower concentration ofsiloxanes therewithin (e.g., compared to the concentration of siloxanesin the gas initially present in at least one of the components). The newgas flows into and out of each component in parallel and/orsimultaneously (e.g., via one or more conduits dedicated to eachcomponent).

Embodiments of the invention may include one or more of the following inany of a variety of combinations. Siloxanes may be removed from the newgas before and/or during supplying the new gas to each of the componentsin parallel. Siloxanes may be removed from the new gas via adsorptionand/or absorption. Siloxanes may be adsorbed by activated carbon, silicagel, polymer beads, and/or one or more molecular sieves. Siloxanes maybe absorbed by an organic solvent, mineral oil, and/or water. Siloxanesmay be removed from the new gas via condensation and/or reaction.Siloxanes may be removed from the new gas by flowing the new gas overand/or through a liquid. At least one component may be configured toallow leakage of gas therefrom. The new gas may be supplied to eachcomponent via a gas inlet thereof (e.g., a gas inlet coupled only to theparticular component). Gas may be exhausted from each component via agas outlet thereof (e.g., via a gas outlet coupled only to theparticular component). At least one gas outlet may be configured torelease gas into a surrounding ambient and/or into an exhaust system.Moisture may be removed from the new gas prior to supplying the new gasto each of the components in parallel. Moisture may be removed from thenew gas after, and/or separately, from siloxane removal from the newgas.

A concentration of siloxanes within at least one component, within newgas supplied to at least one component, and/or gas exhausted from atleast one component may be detected. New gas may be supplied to each ofthe components in parallel only when a detected siloxane concentrationexceeds a threshold. New gas may be supplied to each of the componentsin parallel continuously during operation of the one or more beamemitters. New gas may be supplied to each of the components in parallelat regular intervals, e.g., only when the beam emitters are operating orwhether or not the beam emitters are operating. New gas may be suppliedto each of the components in parallel upon receipt of a command from anoperator (e.g., a human operator). At least one component may behermetically sealed. At least one component may include therewithin oneor more materials that produce siloxanes via outgassing. At least onebeam emitter may include, consist essentially of, or consist of one ormore nitride semiconductor materials. At least one beam emitter mayinclude, consist essentially of, or consist of GaN, AlGaN, InGaN, AlN,InN, and/or an alloy or mixture thereof.

At least one of the components may include, consist essentially of, orconsist of a laser resonator having a plurality of beam emitterstherewithin. Beams emitted by the plurality of beam emitters may becombined into a combined and/or multi-wavelength beam. A first portionof the combined and/or multi-wavelength beam may be transmitted out ofthe laser cavity as an output beam. A second portion of the combinedand/or multi-wavelength beam may be directed back to the plurality ofbeam emitters to stabilize emission thereof (e.g., to form externallasing cavities). The plurality of beam emitters may be cooled, e.g.,via flow of a fluid coolant.

The plurality of components may include, consist essentially of, orconsist of (i) two or more laser resonators each including one or morebeam emitters therein, (ii) a beam-combining module, and (iii) a fiberoptic module. An output beam may be emitted from each of the two or morelaser resonators. Each output beam may be a multi-wavelength beam. Eachoutput beam may itself be a beam formed via combination of multiplebeams within the associated laser resonator. The output beams from thetwo or more laser resonators may be combined into a combined beam withinthe beam-combining module. The combined beam may be coupled into anoptical fiber via, by, or within the fiber optic module. A workpiece maybe processed with the combined beam. Processing the workpiece mayinclude, consist essentially of, or consist of cutting, welding,etching, annealing, drilling, soldering, and/or brazing. Processing theworkpiece may include, consist essentially of, or consist of physicallyaltering at least a portion of a surface of the workpiece.

In another aspect, embodiments of the invention feature a method ofemission (e.g., reliable emission) of one or more beams by a laserapparatus. The laser apparatus includes, consists essentially of, orconsists of a plurality of enclosed components fluidly connected to eachother in series (e.g., via a series of conduits each fluidly couplingtwo of the components together). At least one of the components includesone or more beam emitters therewithin. Each of the components includesgas therewithin. One or more of the components may be sealed orenclosed. The one or more beam emitters are operated to form one or morebeams. Thereduring, new gas is supplied to a first one of theseries-connected components. The new gas has a lower concentration ofsiloxanes therewithin (e.g., compared to the concentration of siloxanesin the gas initially present in at least one of the components). Thesupplied new gas flows sequentially into and out of each of theseries-connected components.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. Siloxanes may be removed from the newgas before and/or during supplying the new gas to the first one of theseries-connected components. Siloxanes may be removed from the new gasvia adsorption and/or absorption. Siloxanes may be adsorbed by activatedcarbon, silica gel, polymer beads, and/or one or more molecular sieves.Siloxanes may be absorbed by an organic solvent, mineral oil, and/orwater. Siloxanes may be removed from the new gas via condensation and/orreaction. Siloxanes may be removed from the new gas by flowing the newgas over and/or through a liquid. At least one component may beconfigured to allow leakage of gas therefrom. Gas (e.g., new gas) may beexhausted from a last one of the series-connected components. Theexhausted gas may be recirculated (e.g., toward the first one of theseries connected components, toward a pump, and/or toward asiloxane-mitigation system), and siloxanes may be removed therefrom forintroduction back to the first one of the series-connected components.Gas (e.g., new gas) may be exhausted from the last one of theseries-connected components into a surrounding ambient and/or into anexhaust system. Moisture may be removed from the new gas prior tosupplying the new gas to the first one of the series-connectedcomponents. Moisture may be removed from the new gas after, and/orseparately, from siloxane removal from the new gas.

A concentration of siloxanes within at least one component, within newgas supplied to the first one of the series-connected components, withingas (e.g., new gas) supplied to at least one component, and/or gasexhausted from at least one component may be detected. New gas may besupplied to the first one of the series-connected components only when adetected siloxane concentration exceeds a threshold. New gas may besupplied to the first one of the series-connected componentscontinuously during operation of the one or more beam emitters. New gasmay be supplied to the first one of the series-connected components atregular intervals, e.g., only when the beam emitters are operating orwhether or not the beam emitters are operating. New gas may be suppliedto the first one of the series-connected components upon receipt of acommand from an operator (e.g., a human operator). At least onecomponent may be hermetically sealed. At least one component may includetherewithin one or more materials that produce siloxanes via outgassing.At least one beam emitter may include, consist essentially of, orconsist of one or more nitride semiconductor materials. At least onebeam emitter may include, consist essentially of, or consist of GaN,AlGaN, InGaN, AlN, InN, and/or an alloy or mixture thereof.

At least one of the components may include, consist essentially of, orconsist of a laser resonator having a plurality of beam emitterstherewithin. Beams emitted by the plurality of beam emitters may becombined into a combined and/or multi-wavelength beam. A first portionof the combined and/or multi-wavelength beam may be transmitted out ofthe laser cavity as an output beam. A second portion of the combinedand/or multi-wavelength beam may be directed back to the plurality ofbeam emitters to stabilize emission thereof (e.g., to form externallasing cavities). The plurality of beam emitters may be cooled, e.g.,via flow of a fluid coolant.

The plurality of components may include, consist essentially of, orconsist of (i) two or more laser resonators each including one or morebeam emitters therein, (ii) a beam-combining module, and (iii) a fiberoptic module. An output beam may be emitted from each of the two or morelaser resonators. Each output beam may be a multi-wavelength beam. Eachoutput beam may itself be a beam formed via combination of multiplebeams within the associated laser resonator. The output beams from thetwo or more laser resonators may be combined into a combined beam withinthe beam-combining module. The combined beam may be coupled into anoptical fiber via, by, or within the fiber optic module. A workpiece maybe processed with the combined beam. Processing the workpiece mayinclude, consist essentially of, or consist of cutting, welding,etching, annealing, drilling, soldering, and/or brazing. Processing theworkpiece may include, consist essentially of, or consist of physicallyaltering at least a portion of a surface of the workpiece.

These and other objects, along with advantages and features of thepresent invention herein disclosed, will become more apparent throughreference to the following description, the accompanying drawings, andthe claims. Furthermore, it is to be understood that the features of thevarious embodiments described herein are not mutually exclusive and mayexist in various combinations and permutations. As used herein, the term“substantially” means ±10%, and in some embodiments, ±5%. The term“consists essentially of” means excluding other materials thatcontribute to function, unless otherwise defined herein. Nonetheless,such other materials may be present, collectively or individually, intrace amounts. Herein, the terms “radiation” and “light” are utilizedinterchangeably unless otherwise indicated. Herein, “downstream” or“optically downstream,” is utilized to indicate the relative placementof a second element that a light beam strikes after encountering a firstelement, the first element being “upstream,” or “optically upstream” ofthe second element. Herein, “optical distance” between two components isthe distance between two components that is actually traveled by lightbeams; the optical distance may be, but is not necessarily, equal to thephysical distance between two components due to, e.g., reflections frommirrors or other changes in propagation direction experienced by thelight traveling from one of the components to the other. Distancesutilized herein may be considered to be “optical distances” unlessotherwise specified.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIG. 1A is a schematic diagram of a laser resonator in accordance withembodiments of the present invention;

FIGS. 1B and 1C are schematic diagrams of laser systems in accordancewith embodiments of the present invention;

FIGS. 2 and 3 are schematic diagrams of laser systems in accordance withembodiments of the present invention;

FIG. 4 is a schematic diagram of a wavelength beam combining (WBC)resonator in accordance with embodiments of the present invention;

FIG. 5A is a schematic view of a first side of a laser resonator inaccordance with various embodiments of the present invention;

FIG. 5B is a schematic view of a second side of a laser resonator inaccordance with various embodiments of the present invention; and

FIG. 6 is a perspective view of a laser engine incorporating multiplelaser resonators in accordance with various embodiments of the presentinvention.

DETAILED DESCRIPTION

FIG. 1A is a simplified schematic cross-sectional view of a resonator100 that may be utilized with embodiments of the present invention. Asshown, the resonator 100 features an enclosed laser cavity 105 that mayconstitute all or only a portion of the interior volume of the resonator100. Disposed within the laser cavity 105 are one or more beam emitters110. Beam emitters 110 in accordance with embodiments of the inventionmay be composed, at least partially, of one or more semiconductormaterials (e.g., nitride semiconductor materials) such as GaN, InGaN,and/or AlGaN. Such beam emitters 110 may include laser diodes and/ordiode bars. In accordance with various embodiments, the laser cavity 105and/or the resonator 100 may be partially or completely sealed via,e.g., one or more o-rings, gaskets, metal seals, and/or epoxy. Invarious embodiments, the laser cavity 105 and/or the resonator 100 maybe partially or completely sealed via welding and/or brazing of all or aportion of an outer edge or perimeter thereof. In various embodiments,the seal may be hermetic, and thus prevent the flow of air or othergaseous species through the seal. In other embodiments, the seal is nothermetic. (As utilized herein, “sealed” means that the cavity,resonator, or region is isolated, hermetically or non-hermetically, fromthe surrounding ambient and from other portions of the resonator orsystem.)

FIG. 1B schematically depicts a laser system 115 in which gas (e.g.,air, nitrogen, or an inert gas such as argon) is supplied to resonator100 and a siloxane-mitigation system 120 in a closed loop. As shown, apump 125 pumps gas through the siloxane-mitigation system 120 and thenceto the resonator 100 via a gas inlet 130. (In embodiments describedherein in which the gas is not air, the pump may be fluidly coupled to agas source containing the desired gas, e.g., one or more cylinders orother containers, or to a “house” source of gas.) The gas flows and/orcirculates within the laser cavity 105 of the resonator 100 before beingpumped back to pump 125 via a gas outlet 135. As shown, system 115 mayalso incorporate an optional desiccant 140 that removes moisture fromthe flowing gas. Although FIG. 1B depicts the desiccant 140 as beingpositioned upstream of the siloxane-mitigation system 120, in variousembodiments the desiccant 140 may be positioned downstream of thesiloxane-mitigation system 120 (and upstream of resonator 100) or evendownstream of resonator 100 (and upstream of pump 125). In variousembodiments, the desiccant 140 may include, consist essentially of, orconsist of one or more materials such as calcium sulfate, silica, silicagel, activated charcoal, or a molecular sieve. In FIG. 1B and otherfigures, the gas flows represented by arrows may be physically suppliedvia one or more conduits (e.g., pipes, tubing, etc.) extending betweenthe various system components.

In various embodiments, the use of desiccant 140 alone (and/or systemsand techniques designed for moisture removal) is insufficient to reducesiloxane concentration within resonator 100 to levels adequately low toensure high-reliability operation. While the removal of moisture fromgas within and/or supplied to resonator 100 may have additionalbeneficial effects, such removal is generally insufficient to adequatelyaddress siloxane-induced issues detailed herein.

The operation of all or a portion of system 115 (e.g., pump 125 and/orsiloxane-mitigation system 120) may be controlled by a controller 145.For example, the controller 145 may operate the pump 125 at intervals,which may be irregularly or regularly scheduled, or the controller 145may operate the pump 125 on demand (e.g., when initiated by anoperator). In other embodiments, the controller 145 operates the pump125 continuously (e.g., during operation of the resonator 100 and/or thebeam emitters 110 therewithin, and/or when the resonator 100 and/or thebeam emitters 110 are not powered or being operated). In variousembodiments, the controller 145 may be responsive to one or moremonitors or sensors for sensing siloxane concentration, and maytherefore operate pump 125 when the siloxane concentration reaches athreshold level. In various embodiments, the controller 145 may evenpower down or power off resonator 100 (and/or one or more beam emitters110) when sensed siloxane concentration within the resonator 100 reachesa threshold level. Such monitors or sensors may be positioned at variouslocations within system 115, e.g., within the laser cavity 105, and/orwithin one or more conduits constituting the gas-flow path indicated inFIG. 1B. Exemplary siloxane sensors may include, but are not limited to,gas chromatography systems, mass spectrometers, and/or atomic emissiondetectors. In various embodiments, one or more sensors may be utilizedto sense the concentration of siloxanes present in one or morecomponents, within one or more conduits coupled to one or morecomponents, and/or to an exhaust stream from one or more components, andsuch sensed concentrations may be reported (e.g., via a display). Thisinformation may be utilized to track the siloxane-mitigation performanceof the system, and/or may be utilized as an indicator for, for example,replacement of consumables (e.g., siloxanes adsorbers or absorbers)within the system when the reported levels reach a threshold level.

The controller 145 may be provided as either software, hardware, or somecombination thereof. For example, the system may be implemented on oneor more conventional server-class computers, such as a PC having a CPUboard containing one or more processors such as the Pentium or Celeronfamily of processors manufactured by Intel Corporation of Santa Clara,Calif, the 680x0 and POWER PC family of processors manufactured byMotorola Corporation of Schaumburg, Ill., and/or the ATHLON line ofprocessors manufactured by Advanced Micro Devices, Inc., of Sunnyvale,Calif. The processor may also include a main memory unit for storingprograms and/or data relating to the methods described herein. Thememory may include random access memory (RAM), read only memory (ROM),and/or FLASH memory residing on commonly available hardware such as oneor more application specific integrated circuits (ASIC), fieldprogrammable gate arrays (FPGA), electrically erasable programmableread-only memories (EEPROM), programmable read-only memories (PROM),programmable logic devices (PLD), or read-only memory devices (ROM). Insome embodiments, the programs may be provided using external RAM and/orROM such as optical disks, magnetic disks, as well as other commonlyused storage devices. For embodiments in which the functions areprovided as one or more software programs, the programs may be writtenin any of a number of high level languages such as FORTRAN, PASCAL,JAVA, C, C++, C #, BASIC, various scripting languages, and/or HTML.Additionally, the software may be implemented in an assembly languagedirected to the microprocessor resident on a target computer; forexample, the software may be implemented in Intel 80×86 assemblylanguage if it is configured to run on an IBM PC or PC clone. Thesoftware may be embodied on an article of manufacture including, but notlimited to, a floppy disk, a jump drive, a hard disk, an optical disk, amagnetic tape, a PROM, an EPROM, EEPROM, field-programmable gate array,or CD-ROM.

In various embodiments, the siloxane-mitigation system 120 may include,consist essentially of, or consist of a material for adsorption of thesiloxane from the gas stream, such as activated carbon, silica gel,polymer beads, or one or more molecular sieves. In addition or instead,the siloxane-mitigation system 120 may include, consist essentially of,or consist of a material (e.g., a liquid) for absorption of the siloxanefrom the gas stream, such as one or more organic solvents, mineral oil,or even water. In the siloxane-mitigation system 120, the gas to bepumped into the laser cavity 105 may flow over and/or through (e.g.,bubbled through) one or more such materials for adsorption and/orabsorption of siloxanes from the gas.

In some embodiments, the siloxane-mitigation system 120 mayalternatively, or in addition, include, consist essentially of, orconsist of a remediation system that removes siloxane from the gasstream via condensation (e.g., one or more cooling systems) and/orreaction (such as catalysis). For example, for condensation, thesiloxane-mitigation system 120 may include, consist essentially of, orconsist of a device or material producing sufficiently low temperatureand/or pressure to condense at least a portion of the siloxanes from thegas. For example, the siloxane-mitigation system 120 may include,consist essentially of, or consist of a refrigeration system and/or heatexchanger to cool the gas to a temperature below approximately 5° C.(for, e.g., removal of about 15%-50% of the siloxanes), or even belowapproximately −25° C. or −30° C. (for, e.g., removal of about 95% ormore of the siloxanes). Catalytic systems in accordance with embodimentsof the invention may include, consist essentially of, or consist of amaterial such as activated alumina (and/or one or more other porousand/or ceramic materials) for reaction (and thus removal) of thesiloxanes from the gas; such catalyst materials may be replenished oneor more times during and/or after operation of the laser system.

FIG. 1C schematically depicts a laser system 150 in which gas (e.g.,air, nitrogen, and/or one or more inert gases such as argon) is suppliedto resonator 100 via siloxane-mitigation system 120 in an open loop. Asshown, the gas is pumped using pump 125, via optional desiccant 140 andsiloxane-mitigation system 120, into the laser cavity 105 of resonator100 via gas inlet 130. In this manner, a positive pressure is formedwithin the laser cavity 105, and gas may escape from the laser cavity105 via gas outlet 135 and be released into the surrounding ambient orinto an exhaust system. In various embodiments, particularly when thelaser cavity 105 is not hermetically sealed, gas may escape (e.g., leak)from the laser cavity 105 through seals and/or walls or other surfacesof the resonator 100 itself, in addition to (or even instead of) leavingthe laser cavity via gas outlet 135. In some such embodiments,therefore, gas outlet 135 may not be present.

FIG. 2 schematically depicts a laser system 200 in which gas (e.g., air,nitrogen, and/or one or more inert gases such as argon) is supplied tomultiple different system components via siloxane-mitigation system 120in parallel. That is, as shown, the gas flows into and out of each ofthe various components via a dedicated path (e.g., via a dedicated gasinlet, gas outlet, and conduits), and gas is not directly exchangedbetween multiple components. One or more pumps 125 may control the flowof gas, which may travel from the siloxane-mitigation system 120 to thevarious system components via an inlet manifold 205. Inlet manifold 205receives the treated gas from the siloxane-mitigation system 120 andsupplies it, via multiple different outlets, to the various systemcomponents. The gas then flows from each component, via a gas outletthereon (e.g., gas outlet 135 on FIGS. 1B and 1C) to an outlet manifold210. Outlet manifold 210 receives the various gas flows, combines them,and supplies the gas back to pump 125 via a gas outlet.

In various embodiments of the invention, system 200 may be applied tomultiple components within a single resonator 100 or to multipledifferent resonators 100 (and/or components thereof). For example, asshown in FIG. 2 , treated gas is supplied to multiple different lasercavities 105-1-105-4, each of which may be disposed within a differentresonator 100. The laser cavities may be optically interfaced with(i.e., supply laser beams to) one or more additional components such asa beam-combining module 215 and/or a fiber optic module 220. Inexemplary embodiments, beam-combining module 215 may contain one or moreoptical elements, such as mirrors, dichroic mirrors, lenses, prisms,dispersive elements, polarization beam combiners, etc., that may combinebeams received from the various laser cavities into one or more outputbeams. In various embodiments, the fiber-optic module may contain, forexample, one or more optical elements for adjusting output laser beams,as well as interface hardware connecting to one or more optical fibersfor coupling of the beams into the optical fiber(s).

FIG. 3 schematically depicts a laser system 300 in which gas (e.g., air,nitrogen, and/or one or more inert gases such as argon) is supplied tomultiple different system components via siloxane-mitigation system 120in series. That is, as shown, the gas flows along a single path thatextends into a first component (e.g., beam-combining module 215 asshown), out of that component and into the next component (e.g., lasercavity 105-1 as shown), and so forth, until the gas is finally exhaustedfrom the final component in the series (e.g., fiber optic module 220 asshown) back to outlet manifold 210 for supply back to pump 125. Thus, inthe technique illustrated in FIG. 3 , gas is introduced into each of thevarious components at different times, and sequentially, whereas in theparallel arrangement depicted in FIG. 2 , gas is introduced into (or atleast flowed to) each of the components substantially simultaneously(depending upon the various lengths of the conduits coupled to each ofthe components). Laser system 300 requires fewer conduits andconnections when compared to laser system 200, although differentcomponents along the gas-flow path may receive gas having differentlevels of purity (e.g., different levels of remnant siloxanes) in someembodiments.

Although only one siloxane-mitigation system 120 is depicted in FIG. 3 ,embodiments of the invention may include one or more additionalsiloxane-mitigation systems disposed between two of the components, inorder to ensure that gas flowing sequentially through all of the variouscomponents maintains a low concentration of siloxanes. In embodimentsfeaturing only one siloxane-mitigation system 120 as depicted in FIG. 3, the siloxane-mitigation system 120 may be disposed upstream of all ofthe components, as shown, or may be disposed between two of thecomponents or downstream of the last component and upstream of the pump125.

Laser systems in accordance with embodiments of the present inventionmay utilize WBC technology and may therefore include WBC laser systemsand related components. FIG. 4 schematically depicts various componentsof a WBC resonator 400 that, in the depicted embodiment, combines thebeams emitted by nine different multi-beam emitters, i.e., emitters fromwhich multiple beams are emitted from a single package, such as diodebars. Embodiments of the invention may be utilized with fewer or morethan nine emitters. In accordance with embodiments of the invention,each emitter may emit a single beam, or, each of the emitters may emitmultiple beams. The emitters in FIG. 4 are depicted as each emitting asingle beam for clarity and convenience of illustration. The view ofFIG. 4 is along the WBC dimension, i.e., the dimension in which thebeams from the bars are combined. The exemplary resonator 400 featuresnine diode bars 405, and each diode bar 405 includes, consistsessentially of, or consists of an array (e.g., one-dimensional array) ofemitters along the WBC dimension. Each emitter of a diode bar 405 mayemit a non-symmetrical beam having a larger divergence in one direction(known as the “fast axis,” here oriented vertically relative to the WBCdimension) and a smaller divergence in the perpendicular direction(known as the “slow axis,” here along the WBC dimension).

In various embodiments, each of the diode bars 405 is associated with(e.g., attached or otherwise optically coupled to) a fast-axiscollimator (FAC)/optical twister microlens assembly that collimates thefast axis of the emitted beams while rotating the fast and slow axes ofthe beams by 90°, such that the slow axis of each emitted beam isperpendicular to the WBC dimension downstream of the microlens assembly.The microlens assembly also converges the chief rays of the emittersfrom each diode bar 405 toward a dispersive element 410. Suitablemicrolens assemblies are described in U.S. Pat. No. 8,553,327, filed onMar. 7, 2011, and U.S. Pat. No. 9,746,679, filed on Jun. 8, 2015, theentire disclosure of each of which is hereby incorporated by referenceherein.

As shown in FIG. 4 , resonator 400 also features a set of SAC lenses (or“slow-axis collimators”) 415, one SAC lens 415 associated with, andreceiving beams from, one of the diode bars 405. Each of the SAC lenses415 collimates the slow axes of the beams emitted from a single diodebar 405. After collimation in the slow axis by the SAC lenses 415, thebeams propagate to a set of interleaving mirrors 420, which redirect thebeams toward the dispersive element 410. The arrangement of theinterleaving mirrors 420 enables the free space between the diode bars405 to be reduced or minimized, and also reduces or minimizes theoverall wavelength locking bandwidth. Upstream of the dispersive element410 (which may include, consist essentially of, or consist of, forexample, a diffraction grating such as the transmissive diffractiongrating depicted in FIG. 4 ), a lens 425 may optionally be utilized tocollimate the sub-beams (i.e., emitted rays other than the chief rays)from the diode bars 405. In various embodiments, the lens 425 isdisposed at an optical distance away from the diode bars 405 that issubstantially equal to the focal length of the lens 425. Note that, invarious embodiments, the overlap of the chief rays at the dispersiveelement 410 is primarily due to the redirection of the interleavingmirrors 420, rather than the focusing power of the lens 425.

Also depicted in FIG. 4 are lenses 430, 435, which form an opticaltelescope for mitigation of optical cross-talk, as disclosed in U.S.Pat. No. 9,256,073, filed on Mar. 15, 2013, and U.S. Pat. No. 9,268,142,filed on Jun. 23, 2015, the entire disclosure of which is herebyincorporated by reference herein. Resonator 400 may also include one ormore folding mirrors 440 for redirection of the beams such that theresonator 400 may fit within a smaller physical footprint. Thedispersive element 410 combines the beams from the diode bars 405 into asingle, multi-wavelength beam, which propagates to a partiallyreflective output coupler 445. The coupler 445 transmits a portion ofthe beam as the output beam of resonator 400 while reflecting anotherportion of the beam back to the dispersive element 410 and thence to thediode bars 405 as feedback to stabilize the emission wavelengths of eachof the beams.

As shown in FIGS. 2 and 3 , in various embodiments of the invention, alaser system incorporates multiple resonators 400, and the output beamsfrom the resonators 400 are combined downstream (e.g., within a housingand/or by one or more optical elements; for example, in beam-combiningmodule 215) into a single output beam that may be directed to aworkpiece for processing (e.g., welding, cutting, annealing, etc.)and/or coupled into an optical fiber (e.g., via fiber optic module 220).

Various embodiments of the invention implement an external cavity lasersystem and reduce the required size of the resonator using a lasercavity that extends along opposing sides of the resonator. FIGS. 5A and5B depict opposing sides of a resonator 500 that collectively constitutea single laser cavity (connected by a central opening, as detailedbelow). In accordance with embodiments of the invention, both sides ofresonator 500 may be sealed, e.g., along a sealing path 505, and gas mayflow into and out of the laser cavity via a gas inlet and a gas outlet(not shown in FIGS. 5A and 5B; see FIGS. 1A-1C). For example, a solidcover plate may be sealed over each side of the resonator 500 along thesealing paths 505 to seal the laser cavity within the resonator 500. Invarious embodiments, each cover plate may be fastened and/or sealed toresonator 500 via fasteners (e.g., screws, bolts, rivets, etc.) thatextend into (and may mechanically engage with, e.g., threadingly engagewith) apertures defined in resonator 500. In other embodiments, eachcover plate may be sealed along its sealing path 505 via a techniquesuch as welding, brazing, or use of an adhesive material.

In various embodiments, the gas inlet and outlet for flow of gas intoand out of the laser cavity of resonator 500 may be disposed on one orboth of the cover plates sealed to the resonator 500 along the sealingpaths 505. Reflectors such as mirrors may be utilized to direct thebeams from one or more beam emitters within the laser cavity, and, sincethe laser cavity extends along both sides, the overall size of theresonator 500 may be correspondingly reduced for the same cavity size(e.g., compared to a resonator having an optical cavity on only oneside).

In the exemplary embodiment shown in FIGS. 5A and 5B, beams from beamemitters (e.g., beam emitters 405 shown in FIG. 4 ) disposed in mountingarea 510 may be focused by a group of lenses (and/or other opticalelements; for example, SAC lenses 415 shown in FIG. 4 ) disposed in lensarea 515 toward a group of mirrors (e.g., interleaving mirrors 420 shownin FIG. 4 ) in a mirror area 520. From mirror area 520, the beams fromthe beam emitters may be directed to another mirror area 525 (containingmultiple reflectors such as mirrors) and thence through an opening 530to the remaining portion of the laser cavity on the other side ofresonator 500. As shown in FIG. 5B, the beams may be directed to amirror area 535 (containing multiple reflectors such as mirrors), whichreflects the beams to a beam-combining area 540. In example embodiments,the beam-combining area 540 may include therewithin the diffusiveelement 410 (and, in some embodiments, the output coupler 445) shown inFIG. 4 . In various embodiments, the beams each have a differentwavelength, and the beams are combined in beam-combining area 540 intoan output beam composed of the multiple wavelengths. The beam from thebeam-combining area 540 may be directed to a mirror 545 (which, invarious embodiments, may be partially reflective output coupler 445) andthence to an output 550 for emission from the resonator 500. Forexample, the output may be a window for emission of the beamtherethrough or an optical coupler configured to connect to an opticalfiber. In various embodiments, the output may transmit the beam to afiber-optic module (e.g., fiber optic module 220) for coupling into anoptical fiber. In other embodiments, the output beam may be transmittedto a beam-combining module (see, e.g., FIG. 2 ), and combined withoutput beams emitted by other resonators. The resulting combined beammay be transmitted to a fiber-optic module (e.g., fiber optic module220) for coupling into an optical fiber, and/or utilized for processingof a workpiece.

As shown in FIG. 5B, resonator 500 may also include a liquid coolantcavity 555. The liquid coolant cavity 555 is, in various embodiments, ahollow cavity configured to contain liquid coolant (e.g., water, glycol,or other heat-transfer fluid) directly beneath the mounting area 510.The liquid coolant may flow into and out of the cavity 555 via a fluidinlet and a fluid outlet (not shown), which may be fluidly coupled to,e.g., a reservoir of coolant and/or a heat exchanger for cooling fluidheated by the beam emitters. As detailed in the '134 application,embodiments of the invention may feature a control system that controlsthe rate of fluid flow into and out of the cavity 555 based on one ormore sensed characteristics, e.g., temperature of the beam emitters, thecooling fluid, and/or one or more other components of and/or positionswithin resonator 500. In various embodiments, the laser cavity ofresonator 500 may be sealed without sealing or covering of the opticalcoolant cavity 555, thereby leaving the optical coolant cavity 555accessible (e.g., for service, maintenance, or cleaning) without theneed to unseal or expose the more delicate components disposed withinthe laser cavity.

In various embodiments of the invention, a laser system incorporatesmultiple resonators 100, as shown in FIGS. 2 and 3 , and the outputbeams from the resonators 100 are combined downstream (e.g., within amaster housing and/or by one or more optical elements) into a singleoutput beam that may be directed to a workpiece for processing (e.g.,welding, cutting, annealing, etc.) and/or coupled into an optical fiber.For example, FIG. 6 depicts an exemplary laser system (or “laserengine”) 600 in accordance with embodiments of the invention. In lasersystem 600, multiple laser resonators 100 are mounted within a masterhousing 605, and the output beams from the resonators 100 are emittedinto a beam-combining module 610 and thence to a fiber optic module 615.In exemplary embodiments, beam-combining module 610 may contain one ormore optical elements, such as mirrors, dichroic mirrors, lenses,prisms, dispersive elements, polarization beam combiners, etc., that maycombine beams received from the various resonators into one or moreoutput beams. In various embodiments, the fiber-optic module 615 maycontain, for example, one or more optical elements for adjusting outputlaser beams, as well as interface hardware connecting to one or moreoptical fibers for coupling of the beams into the optical fiber(s).While laser engine 600 is depicted as including four resonators 100,laser engines in accordance with embodiments of the invention mayinclude one, two, three, or five or more laser resonators. Variouscomponents of siloxane-mitigation systems as described herein are notshown in FIG. 6 for clarity but are illustrated schematically in FIGS. 2and 3 . In various embodiments of the invention, an open-loop or closedloop siloxane-mitigation system utilized to reduce or minimize theconcentration of siloxanes within a resonator 100 may be shared (e.g.,in parallel or in series) with other resonators in a laser engine and/orwith other components of the laser engine such as the beam-combiningmodule and/or fiber optic module.

As mentioned herein, in various embodiments of the present invention,the output beams of the laser systems or laser resonators may bepropagated, e.g., via a fiber optic module, to a delivery optical fiber(which may be coupled to a laser delivery head) and/or utilized toprocess a workpiece. In various embodiments, a laser head contains oneor more optical elements utilized to focus the output beam onto aworkpiece for processing thereof. For example, laser heads in accordancewith embodiments of the invention may include one or more collimators(i.e., collimating lenses) and/or focusing optics (e.g., one or morefocusing lenses). A laser head may not include a collimator if thebeam(s) entering the laser head are already collimated. Laser heads inaccordance with various embodiments may also include one or moreprotective window, a focus-adjustment mechanism (manual or automatic,e.g., one or more dials and/or switches and/or selection buttons). Laserheads may also include one or more monitoring systems for, e.g., laserpower, target material temperature and/or reflectivity, plasma spectrum,etc. A laser head may also include optical elements for beam shapingand/or adjustment of beam quality (e.g., variable BPP) and may alsoinclude control systems for polarization of the beam and/or thetrajectory of the focusing spot. In various embodiments, the laser headmay include one or more optical elements (e.g., lenses) and a lensmanipulation system for selection and/or positioning thereof for, e.g.,alteration of beam shape and/or BPP of the output beam, as detailed inU.S. patent application Ser. No. 15/188,076, filed on Jun. 21, 2016, theentire disclosure of which is incorporated by reference herein.Exemplary processes include cutting, piercing, welding, brazing,annealing, etc. The output beam may be translated relative to theworkpiece (e.g., via translation of the beam and/or the workpiece) totraverse a processing path on or across at least a portion of theworkpiece.

In embodiments utilizing an optical delivery fiber, the optical fibermay have many different internal configurations and geometries. Forexample, the optical fiber may include, consist essentially of, orconsist of a central core region and an annular core region separated byan inner cladding layer. One or more outer cladding layers may bedisposed around the annular core region. Embodiments of the inventionmay incorporate optical fibers having configurations described in U.S.patent application Ser. No. 15/479,745, filed on Apr. 5, 2017, and U.S.patent application Ser. No. 16/675,655, filed on Nov. 6, 2019, theentire disclosure of each of which is incorporated by reference herein.

In various embodiments, the controller may control the motion of thelaser head or output beam relative to the workpiece via control of,e.g., one or more actuators. The controller may also operate aconventional positioning system configured to cause relative movementbetween the output laser beam and the workpiece being processed. Forexample, the positioning system may be any controllable optical,mechanical or opto-mechanical system for directing the beam through aprocessing path along a two- or three-dimensional workpiece. Duringprocessing, the controller may operate the positioning system and thelaser system so that the laser beam traverses a processing path alongthe workpiece. The processing path may be provided by a user and storedin an onboard or remote memory, which may also store parameters relatingto the type of processing (cutting, welding, etc.) and the beamparameters necessary to carry out that processing. The stored values mayinclude, for example, beam wavelengths, beam shapes, beam polarizations,etc., suitable for various processes of the material (e.g., piercing,cutting, welding, etc.), the type of processing, and/or the geometry ofthe processing path.

As is well understood in the plotting and scanning art, the requisiterelative motion between the output beam and the workpiece may beproduced by optical deflection of the beam using a movable mirror,physical movement of the laser using a gantry, lead-screw or otherarrangement, and/or a mechanical arrangement for moving the workpiecerather than (or in addition to) the beam. The controller may, in someembodiments, receive feedback regarding the position and/or processingefficacy of the beam relative to the workpiece from a feedback unit,which will be connected to suitable monitoring sensors.

In addition, the laser system may incorporate one or more systems fordetecting the thickness of the workpiece and/or heights of featuresthereon. For example, the laser system may incorporate systems (orcomponents thereof) for interferometric depth measurement of theworkpiece, as detailed in U.S. patent application Ser. No. 14/676,070,filed on Apr. 1, 2015, the entire disclosure of which is incorporated byreference herein. Such depth or thickness information may be utilized bythe controller to control the output beam to optimize the processing(e.g., cutting, piercing, or welding) of the workpiece, e.g., inaccordance with records in the database corresponding to the type ofmaterial being processed.

The terms and expressions employed herein are used as terms ofdescription and not of limitation, and there is no intention, in the useof such terms and expressions, of excluding any equivalents of thefeatures shown and described or portions thereof, but it is recognizedthat various modifications are possible within the scope of theinvention claimed.

1.-161. (canceled)
 162. A laser apparatus comprising: a laser systemcomprising a plurality of enclosed components, at least one of thecomponents comprising one or more beam emitters therewithin, wherein (i)each component comprises a gas inlet configured to permit ingress of gasinto the component and a gas outlet configured to permit egress of gasout of the component, and (ii) the components are fluidly connected toeach other in series; a pump, different from the plurality of enclosedcomponents, for supplying gas to the gas inlet of a first one of thecomponents, whereby the supplied gas flows sequentially into and out ofeach of the series-connected components; and a siloxane-mitigationsystem, different from the plurality of enclosed components, configuredto remove siloxanes from gas supplied by the pump.
 163. The apparatus ofclaim 162, further comprising an inlet manifold, different from theplurality of enclosed components, fluidly coupled to the gas inlet ofthe first one of the components, wherein the pump supplies gas to theinlet manifold for supply to the gas inlet of the first one of theenclosed components.
 164. The apparatus of claim 162, wherein at leastone of the enclosed components of the laser system (i) comprisestherewithin one or more optical elements configured to focus and/ordirect laser beams, and (ii) does not comprise a beam emittertherewithin.
 165. The apparatus of claim 162, further comprising anoutlet manifold, different from the plurality of enclosed components,fluidly coupled to the gas outlet of a last one of the enclosedcomponents.
 166. The apparatus of claim 165, wherein the pump is fluidlyconnected to the outlet manifold.
 167. The apparatus of claim 165,wherein the outlet manifold is configured to release gas into asurrounding ambient.
 168. The apparatus of claim 162, wherein a gasoutlet of a last one of the enclosed components is fluidly connected tothe pump.
 169. The apparatus of claim 162, wherein a gas outlet of alast one of the enclosed components is configured to release gas into asurrounding ambient.
 170. The apparatus of claim 162, further comprisinga desiccant positioned to remove moisture from gas supplied by the pump.171. The apparatus of claim 162, wherein the siloxane-mitigation systemcomprises a siloxane-adsorbing material and/or a siloxane-absorbingmaterial.
 172. The apparatus of claim 162, wherein thesiloxane-mitigation system comprises a remediation system configured toremove siloxanes from the gas via at least one of condensation orreaction.
 173. The apparatus of claim 162, wherein thesiloxane-mitigation system comprises a liquid over and/or through whichgas supplied by the pump is flowed.
 174. The apparatus of claim 162,further comprising one or more sensors configured to detect siloxaneswithin at least one enclosed component and/or within one or moreconduits fluidly connected to at least one of the pump, at least oneenclosed component, or the siloxane-mitigation system.
 175. Theapparatus of claim 162, wherein one of the components comprises a laserresonator having an enclosed laser cavity, the laser cavity comprisingtherewithin: a plurality of beam emitters each emitting a beam having adifferent wavelength; a dispersive element configured to receive beamsemitted by the plurality of emitters and combine the beams into amulti-wavelength beam; and disposed optically downstream of thedispersive element, a partially reflective output coupler configured to(i) receive the multi-wavelength beam, (ii) transmit a first portion ofthe multi-wavelength beam as an output beam, and (iii) reflect a secondportion of the multi-wavelength beam back toward the dispersive element.176. The apparatus of claim 175, wherein: the laser cavity comprises aplatform having top and bottom opposed sides and defining an openingtherethrough; the plurality of beam emitters is disposed over the topside of the platform, the beams emitted thereby being directed throughthe opening in the platform to the bottom side of the platform; and thedispersive element is disposed over the bottom side of the platform andpositioned to receive the beams directed through the opening.
 177. Theapparatus of claim 176, wherein the partially reflective output coupleris disposed over the bottom side of the platform.
 178. The apparatus ofclaim 175, wherein the laser cavity comprises therewithin: a pluralityof slow-axis collimation lenses disposed optically downstream of theplurality of beam emitters, each slow-axis collimation lens configuredto receive one or more beams from one of the beam emitters; and aplurality of folding mirrors disposed optically downstream of theslow-axis collimation lenses and optically upstream of the dispersiveelement.
 179. The apparatus of claim 178, wherein: the laser cavitycomprises a platform having top and bottom opposed sides; the pluralityof beam emitters is disposed over the top side of the platform; theplurality of slow-axis collimation lenses and the plurality of foldingmirrors are disposed over the top side of the platform; the dispersiveelement is disposed over the bottom side of the platform; the platformdefines an opening therethrough, and the beams emitted by the pluralityof beam emitters are directed, from the top side of the platform to thebottom side of the platform, to the dispersive element through theopening; and the partially reflective output coupler is disposed overthe bottom side of the platform.
 180. The apparatus of claim 162,wherein the plurality of enclosed components of the laser systemcomprises a plurality of laser resonators, each laser resonator (i)being enclosed within a separate enclosure fluidly coupled to adifferent one of the gas inlets and (ii) comprising a plurality of beamemitters therewithin and being configured to combine beams emitted bythe beam emitters into a combined beam.
 181. The apparatus of claim 180,further comprising: a beam-combining module, separate from the laserresonators, configured to receive the combined beams from the laserresonators and combine the combined beams into an output beam; and afiber optic module, separate from the laser resonators, configured toreceive the output beam from the beam-combining module and supply theoutput beam to an optical fiber.
 182. The apparatus of claim 162,further comprising a computer-based controller configured to operate thepump.
 183. The apparatus of claim 182, further comprising one or moresensors configured to detect siloxanes within at least one enclosedcomponent and/or within one or more conduits fluidly connected to atleast one of the pump, at least one enclosed component, or thesiloxane-mitigation system, wherein the controller is responsive tosignals received from the one or more sensors.
 184. The apparatus ofclaim 183, wherein the controller is configured to operate the pump onlywhen a siloxane concentration detected by at least one of the sensorsexceeds a threshold.
 185. The apparatus of claim 183, wherein thecontroller is configured to power down or power off the one or more beamemitters when a siloxane concentration detected by at least one of thesensors exceeds a threshold.
 186. The apparatus of claim 182, whereinthe controller is configured to operate the pump continuously, at leastduring operation of the one or more beam emitters.
 187. The apparatus ofclaim 182, wherein the controller is configured to operate the pump atregular, predetermined intervals, irrespective of a siloxaneconcentration within one or more of the components.